The Biological Survey of the Barlee-Menzies Study Area
Total Page：16
File Type：pdf, Size：1020Kb
VEGETATION AND FLORA G.J. Keighery, A.V. Milewski and N.J. Hall Background During the present survey of the Barlee-Menzies Study Area, vegetation was described from plotless sample sites as specified by Biological Surveys Committee of Western Australia (1984). From the survey, 24 vegetation sites were selected to cover the 8landform units across the Study Area. The locations of these vegetation sample sites are provided in Appendix 1 and, except for BM24, are shown in Figure 2. The sites are broadly classified, on the basis of structure and species composition of the upper stratum, into vegetation types. Two of the types (Breakaway and Granite) were referred to as vegetation complexes, because their structure and species composition changed markedly over distances of a few metres. The vegetation sites are described in Appendix 1, together with relevant data on geology, landforms and soils. Although these detailed site descriptions are central to this paper, they were too bulky to be presented in text or as tables. Table 1 summarises the relationships between landform units and elements, lithology, soils, vegetation structure, floristic composition and site codes. This Table has been designed to provide a cross-reference summary, and to be read in conjunction with the text below, in which brief vegetation descriptions are integrated with landform units. Full descriptions of the 24 vegetation sample sites are detailed in Appendix 1. Reference to Appendix 2 provides a complete listing by landform unit, of the flora recorded during the biological survey of the Barlee-Menzies Study Area. Plates 1-10 provide examples of the various vegetation types present in the Study Area (see Appendix 1). Vegetation Descriptions Breakaways (B) Occasional breakaways occurred throughout the study area, particularly in the north-east. Many are associated with weathered outcrops of granite, but, particularly in the south-east, lateritic breakaways were common. Four distinct elements comprise the breakaway landform: summit flats, scree slopes, colluvial base and drainage channels. Species composition varied across the study area, with the summit vegetation being Allocasuarina corniculata lA. acutivalvis shrublands in the south-west and Acacia aneura lA. quadrimarginea elsewhere (resembling that found on Granite Exposures). On the summit and scree slopes were scattered trees of Casuarina eristata and Eucalyptus ewartiana, tall shrubs of Eremophila spp., low shrubs of Ptilotus obovatus, perennial herbaceous plants of Sclerolaena spp. and ephemeral species (Helipterum spp., Angianthus spp., Gnephosis spp. and Ptilotus spp.). Ephemerals were generally uncommon. Colluvial slopes on the southern margins supported low woodlands of Eucalyptus capillosa. Drainage channels in the southern margins supported woodlands of E. loxophleba or E. salubris. Dunefields (D) Dunefields associated with Salt Lake Features were uncommon in the Barlee-Menzies Study Area. These bore trees of Eucalyptus and low trees or tall shrubs e.g. Pittosporum 183 Table 1 Relationship between landforms, lithology, soils, vegetation structure and floristic composition at sites sampled or visited in the Barlee-Menzies Study Area. Lithological surfaces follow those devised for the map sheets Barlee (Walker & Blight 1983) and Menzies (Kriewaldt 1970). Vegetation Sites Landform Lithological Surface Soil Vegetation Type Barlee Menzies (Appendix I)' BREAKAWAY (B) Slopes and Tl,Qz Qt, Qtl, Gritty Loams Eucalyptus capillosa Low Woodland summits Qqz Eucalyptus loxophleba Mallee BMl Colluvial slopes Qz Qqs, Qqz Gritty Loams Acacia aneura Tall Shrubland Acacia quadrimarginea Tall Shrubland Breakaway Complex DUNEFlELDS (D) Slopes, summits Qs,Qg Qts, Qak Deep Sands and Acacia aneura Low Woodland and swales Aeolian Sands Callitris columellaris Low Woodland Casuarina cristata Low Woodland Eucalyptus ceratocorys Mallee BM24 ...... Eucalyptus gracilis Mallee 00 .j:. Callitris preissii Tall Shrubland Grevillea juncifolia Tall Shrubland GRANITE EXPOSURES (G) BM4 Skeletal soil sheets Ag Ag Granitic Soils Granite Complex BM2 Inner aprons Ag,Qc Ag,Qpm Granitic Soils Acacia burkittii Tall Shrubland Acacia quadrimarginea Tall Shrubland Acacia tetragonophylla Tall Shrubland Outer aprons Qc Qpm Granitic Soils Eucalyptus ewartiana Mallee Eucalyptus loxophleba Mallee Acacia aneura/A. ramulosa Tall Shrubland BM3 HILLS, GRANITE (HG) Slopes and summits Ag Ag Granitic Soils Acacia quadrimarginea Tall Shrubland HILLS, BANDED IRONSTONE (HI) Slopes and summits Aiw Alb Red Sands Acacia aneura Tall Shrubland BM6 Allocasuarina acutivalvis Tall Shrubland Dryandra arborea Tall Shrubland BM7 Slopes Aiw Qtc Red Sands and Eucalyptus ebbanoensis Low Woodland BM5 Red Earths Acacia quadrimarginea Tall Shrubland Eucalyptus ebbanoensis Mallee HILLS, GREENSTONE (HN) Slopes and summits Ab, Ad Alv Shallow Calcareous Acacia aneura Tall Shrubland Earths Lower slopes Shallow Calcareous Acacia aneura Low Woodland Earths SALT LAKE FEATURES (L) Saline flats, lake Ql Qra Saline Soils Frankenia Low Shrubland floors and margins Halosarcia Low Shrubland BMII Claypans and Qg,Qc, Qak, Qo Sub-saline Soils Cratystylis subspinescens Low Shrubland damp flats Qps and Alluvium Maireana Low Shrubland Salt Lake Margin Complex Well-drained flats Qg, Qpf, Qas, Qak Aeolian Sands and Casuarina cristata Low Woodland BM8 ...... 00 and dunes Qps Aeolian Loams Eucalyptusformanii Low Woodland Ut Eucalyptus clelandii Low Woodland Acacia ramulosa Tall Shrubland Dodonaea angustissima Tall Shrubland BM9 Eremophila miniata Tall Shrubland BMIO Atriplex Low Shrubland SANDPLAIN (S) Flat plains Tl Qtg, Qtn Gravelly Sands Acacia coolgardiensis Tall Shrubland BM-I 5 Acacia resinomarginea Tall Shrubland Allocasuarina acutivalvis Tall Shrubland Ts Qts Deep Sands Acacia aneura Low Woodland Eucalyptus leptopoda Mallee BMl2 Eucalyptus oldfieldii Mallee BMl3 Banksia elderiana Tall Shrubland BMI4· UNDULATING PLAIN, BANDED IRONSTONE (UI) Ridges and Aiw,TI, Alb, Qtc, Red Sands and Eucalyptus ebbanoensis Low Woodland colluvial flats Ag Qpa Red Earths Acacia aneura Low Woodland Table 1 (cont.) Landfonn LithoIogical Surface Soil Vegetation Type Vegetation Sites Barlee Menzies (Appendix I)" UNDULATING PLAIN, GREENSTONE (UN) Colluvial flats Ad, Aus, Qqc Deep Calcareous Eucalyptus clelandii Low Woodland Ab, Alp, Earths Eucalyptus longicornis Low Woodland Aur, Aup, Eucalyptus salubris Low Woodland BMI6 Qc Eucalyptus transcontinentalis Low Woodland Maireana pyramidata Low Shrubland Slopes and ridges Aab, Tl, AIk, A2v, Shallow Calcareous Casuarina cristata Low Woodland BMI? Aiw A2r, Earths and Acacia aneura Low Woodland BMI8 Qqf Red Sands Acacia aneura Tall Shrubland (icacia Tall Shrubland ...... BROAD VALLEY (V) 0\00 Flat and gentle Qc, Ts, Qps Red Sands and Callitris columellaris Low Woodland BM23 undulating plains Qz,Qs AeoIian Loams Eucalyptus jormanii Low Woodland BM20 Eucalyptus transcontinentalis Low Woodland BM2l Valley slopes Qc Qpa, Qqs Shallow Calcareous Eucalyptus longicornis Low Woodland BMI9 Earths Eucalyptus oleosa Low Woodland Red Sands Eucalyptus loxophleba Low Woodland Qz,Ag Qqa, Qqz Red Earths Acacia aneura Low Woodland BM22 Valley bottoms Qa Qpv, Qqs Deep Calcareous Earths Eucalyptus salmonophloia Low Woodland Eucalyptus salubris Low Woodland a A total of about 50 vegetation sites were sampled, of which a representative set of 24 are presented in detail as Appendix 1. (Due to poor vehicle access, two ofthese sites are peripheral to the Study Area.) The balance ofthe sampled sites are held as data sheets at the W.A. Wildlife Research Centre, Perth. phylliraeoides, Acacia tetragonophylla, Grevillea sarissa, Dodonaea angustlsslma and Eremophila miniata. Ephemerals were common and contained some distinctive elements such as Gnephosis macrocephala. Dunefields associated with Sandplains shared few structural or floristic links with salt lake dunefields. Here Callitris preissii was dominant instead of C. columellaris, Chenopodiaceae were absent, and there was a wide variety of mallee Eucalyptus species and south-western floristic elements, such as Caustis dioica, Chamelaucium ciliatum, Lechenaultia brevifolia and Hybanthus floribundus. This was especially true of Dunefields at the southern edge of the Study Area, such as those in the Riverina area (see site BM24, which although in the Edjudina-Menzies Study Area (Fig. 1), is included in Appendix I to illustrate this point. Dunefields associated with Sandplains occurred on the eastern boundary of the Study Area. Dune slopes supported Eucalyptus gracilis and E. rigidula mallees with tall shrubs of Callitris preissii spp. verrucosa over low shrubs and the hummock grass Plectrachne rigidissima. Shrublands that included Grevillea didymobotrya, G. juncifolia and Hakea multilineata dominated the dune crests. Flats between the dunes were characterised by mallees such as Eucalyptus ceratocorys over Melaleuca uncinata, Xanthorrhoea thorntonii and Triodia basedowii. Granite Exposures (G) The vegetation associated with Granite Exposures in the Barlee-Menzies Study Area formed a complex pattern rather than a single extensive community. This was closely tied to microsite variation of the neutral and gritty loamy sands of the soil sheets and their peripheral aprons. Sparse vegetation occurred on the exposed rock itself and the inner apron. Shrubs, mainly Acacia species were scarce and the main cover was of low annual grasses (e.g. Eragrostis, Aristida, Tripogon) and ephemerals of Gnephosis and other dwarf Asteraceae, Calandrinia and Goodenia.